Block input to objects lying under already-hit hitcircles when classic note lock is active

[bdach]

Closes #24626

In the issue thread, I stated that this would be "fixed" by #24280; as it turns out upon further investigation that was not the case, and the test cases I had only "worked" due to specific timings. However, as it also turns out, the API surface that permits hit circles to block input on objects underneath them already exists, and makes implementing this relatively painless. So I'm PRing this as a RFC to see if this is something that would be considered acceptable.

The behaviour proposed by this PR is as follows:

• With classic mod disabled, already-judged circles allow input to reach other objects underneath them.
• With classic mod enabled (specifically, with the "classic note lock" option enabled), already-judged circles block input from reaching objects underneath them.

Test coverage for both behaviours above is included in 40d1196.

Videos for reference:

master

2023-09-05.23-00-13.mp4

this PR

2023-09-05.23-02-31.mp4

stable

2023-09-05.23-01-44.mp4